Agricultural or farm implements of various types have been used throughout the years to loosen the soil or ground. Following a harvest of crop materials, it is well known that a tractor or other suitable off-highway machine draws a plowing implement across a field. Such a plowing implement or system typically comprises a series or gang of moldboard plows that condition the field as they are drawn thereacross. Each moldboard plow operates at about 8 or 10 inches below the ground surface. As the plow is drawn across the field, a strip of ground is turned over onto a furrow formed by a previous pass of the plow system.
When a moldboard plow is used repeatedly to condition the field at the same depth, a layer of highly compacted soil is formed beneath the surface. Continuous passes of the tractor or other off-highway machine across the field exacerbates soil compaction. As will be appreciated by those skilled in the art, flood irrigation techniques and heavy rains furthermore tend to compact the soil. That area of compacted soil or ground beneath the upper surface is commonly referred to, and will be referred to herein, as "hard pan." The disadvantage of a hard pan area in the field is that, due to its compaction, roots of plants have difficulty in penetrating the ground beneath the hard pan. Also, rain water has a tendency to drain over and across the hard pan rather than being absorbed into the ground.
Besides creating a hard pan, a potential disadvantage associated with moldboard plowing results because when the ground is completely turned over, the overturned soil is exposed to erosion due to wind and water flow. Accordingly, and in those situations where it is applicable, some farmers have abandoned moldboard plowing. In parts of the country, it has been found that it is not essential to turn the soil by means of conventional plowing. Because relatively large and relatively heavy off-highway machines continue to be drawn across the field, however, the problem of soil compaction or hard pan remains. As mentioned above, flood irrigation techniques and heavy rains tend to add to soil compaction problems.
Various deep tillage implements have been devised as a solution to the hard pan problem. Such implements, commonly referred to as subsoiler units are drawn behind the tractor and through the ground at a sufficient subsoiling depth to break up or shatter the hard pan thereby allowing water and air to readily penetrate the ground instead of merely running off the hard pan. The presence of subterranean rocks and roots, however, create other problems for the subsoiler units.
A conventional subsoiler unit includes a vertically elongated support or shank having an upper end connected to a tool bar assembly with a point assembly attached to a lower end thereof. A typical point assembly for a subsoiler unit includes a unilateral structure comprised of a ground breaking tooth that connects to an projects forwardly from the lower end of the support with integral wings transversely extending from opposite sides of the tooth.
Besides the inherent breakage problems that result when the point assembly engages a subterranean rock or root, conventional point assemblies are not long lasting because of rapid and extensive wear immediately behind and for a considerable distance rearwardly of the leading cutting edges as well as in other areas such as along the sides of the tooth and the leading and transverse faces of the wings. Similar wear problems are presented for the supports upon which the point assemblies are mounted especially on their front surfaces which immediately contact the ground as the subsoiler unit is pulled across the field.
Because of its subterranean operation, the operator of the implement cannot always timely appreciate when the point assembly has been dulled or even broken. As will be appreciated, as the point assembly wears or becomes blunt from breakage, the draft forces applied to the off-highway machine are significantly increased thus increasing the power requirements and energy required to pull the implement across the field.
Thus, there is a need and a desire for a subsoiler plow unit that performs a relatively wide ground shattering pattern in the subsoil to provide extensive and even distribution of plant nutrients, while promoting root growth of the plants and at the same time will be reasonable in its power requirements.